In wireless communications, since the wireless communication devices communicate via a common air interface, their signals are not isolated from each other. This fact may results in two effects, i.e., i) broadcast: signals from any one transmitter may be received by multiple receivers, and ii) superposition: a wireless receiver receives signals from multiple transmitters, with their signals superimposed on top of each other. Thus, interference may result from the two effects. In some systems, mobility management may enable cellular networks to locate moving user equipments (UEs) for call delivery and to maintain connections when the UEs move into a new cell/service area, this process is called handover, or handoff. While performing handover, the UEs may connect to more than one access device (e.g., base stations) simultaneously and use a certain form of signaling diversity to combine downlink signals from the more than one access device. In some instances, this technique is called soft handover. Soft handover may be used to transmit the same data from the more than one base station to one UE simultaneously to improve reliability of transmissions. However, downlink signals intended for different UEs may cause interferences to each other at the UE. Similarly, for some other joint transmission scenario (e.g., Coordinated Multi-Point (CoMP)), multiple transmitters may jointly transmit signals that are intended to different receivers. For a particular receiver, transmit signals intended to other receivers may be perceived as interference.
In some systems, schemes for interference management may include decoding the transmitted signal by treating interferences as noise, and orthogonalizing channel resources for multiple access of wireless communication devices by assigning different frequency channels, time slots, spatial paths and/or codes to different resources (e.g., frequency division multiple access (FDMA)/time division multiple access (TDMA)/code division multiple access (CDMA)/orthogonal frequency division multiple access (OFDMA)). In some systems, each of multiple transmitters may communicate with one corresponding receiver. If each of the multiple transmitters knows perfect global channel knowledge about all channels in the system, an interference alignment (IA) technique may be used for interference management. Using IA, multiple senders may encode signals by expanding the dimension of the signals and align interferences to at least a portion of the expanded dimension in order to manage interference caused at the corresponding receiver.
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